That is total bullshit. All you should really have to have in order to keep a conversation private is the intentions. Even if it's a plain text email, only myself and the recipient of the email address should have the privilege of it's contents. If you want you can agree to let the provider use an automated system to scan for keyword for ads or whatever, but no one other than the recipients and agreed upon thrid parties should have permission to read those messages and anyone else doing so should be punished by law. We need to add an amendment which augments the 1st to say this clearly.